Art of refining hydrocarbon oils



Dec. 12, 1933. E C. HERTHEL ART OF REFINING HYDROCARBON OILS Filed DGO.31. 1931 NVENTOR 1/gene C//eff/le/ ATTORNEYS 'was Patented Dec. l2, 1933UNITED STATESl ART OF REFINING HYDROCARBON OILS Eugene C. Herthel,Flossmoor, Ill., assignor to Sinclair Refining Company, New York, N. Y.,a corporation of Maine Application December 31, 1931 Serial No. 584,069

2 claims. (c1. 19t- 147) This invention relates to improvements in themanufacture of gasoline by cracking higher boiling hydrocarbon oils,such as gas oil, at temperatures exceeding 900" F. to produce crackedgasoline of high anti-knock value.

The severe cracking temperatures-utilized to produce gasoline of highanti-knock value, temperatures exceeding 900 F. for example, tend toproduce gasoline fractions including lower boiling constituents, lowerboiling within the range of the gasoline fraction, in highconcentration, the production of such low boiling gasoline constituentsaccompanying, within limits, the'production of even lower boilingconstituents incondensable at ordinary atmospheric temperatures andpressure. `These severe cracking temperatures also tend to produceunstable hydrocarbon constituents which, although initially within Vtheboiling range of gasoline, tend to polymerize to form higher boilingpolymers, gums for example.

Such gasolines requireV stabilization both physically and chemically. Y.i v 'I'his invention combines a physical stabilization and a chemicalstabilization in a particularly advantageous manner to afford severaladvantages with respect to economy and simplicity. The physicalstabilization is; effected by fractionation under increased pressure,following .fractionationv under lower` pressure to separateYconstituents higher boiling thansuitable as components of the gasolineproduct,v and the chemical stabilization is effected by digestion withan adsorptive catalyst, fullers earth or similar clays for example,under elevated pressure, this'elevated pressure being maintained throughthe fractionating operation, for physical stabilization, and thedigesting operation, for chemical stabilization, the heat available fromthis fractionating operation being utilized in this digesting operation.

The invention will be further described inconnection with theaccompanying drawing, vwhich illustrates, diagrammatically andconventionally, one form of apparatus adapted for the practice of theprocess of the invention as utilized in conjunction with one type ofcracking system.' It will be understood that other forms of apparatusmay be used for practicing the invention and that the invention isuseful in conjunction with other types of cracking systems.

Of the apparatus illustrated in the accompanying drawing, this inventionrelates more particularly to the operations carried out in thefractionating tower 1, the condenser 2, the receiver 3, the compressor4, the condenser 5, the separaproduct separated in the fractionatingtower 1,

or part of this fraction, is supplied through connections 16 and 17 tothe mixing tank'14 by means of vpump 18. Part of this fraction may bedischarged through connection 19. Part of this fraction may beintroduced through connection 20 into the transfer connection 21 betweenthe cracking heater discharge and the evaporator 12 by means of pump 22.The stock mixture from the tank 14 is forced through the cracking heaterY 11 into the evaporator 1-2 by means of pump 23, 75

connections 24"and 25 connecting the mixing tank 14, the pump 23 and thecracking heater inlet. AA pressure reducing valve 26 is provided inthe'cracking heater discharge for maintaining a' substantialsuperatmospheric pressure in the 80 cracking heater 11 and for effectingreduction of pressure between the cracking heater discharge and theevaporator 12. Tar is discharged from the lower part of the evaporator12 through connection27 and cooler 28. A reiiuxing medi- 85 um, a partofthe same raw stock supplied to the mixingtank 14 through connection 13for example, may be suppliedfto the upper partfof the evaporator 12through connection 29, and the operation of the evaporator may becontrolled by regulation of the rate at which the refluxing medium is sosupplied. The mixture of vapors and gasesV separated in the evaporator.12 passes from the'upper part oi-the evaporator 12 through connection301:0 the lower part ofthe fraction- 95 ating tower 1.,V A reiiuxcondenser 31 is provided for controlling the *operation of thefractionating tower 1, control being afforded by regulation of the rateat which an appropriate cooling medium is Vcirculated therethrough, bymeans of connections32 and 33. The mixture of vapors and gasesseparated' in the fractionating tower" 1 passes from the fractionatingtower 1 to the reiiux condenser 31 through connection 35, condensateformed and separated in the reux condenser 31 105 is returned, orrefluxed, to the upper part of the fractionating tower 1 throughconnection 34, and the remaining mixture passes from the refluxcondenser 31 to the condenser 2 through connection 36. Connection 3'7,discharging through 110 In this particular cracking 60 cooler 38, isprovided for separating an intermediate fraction in the fractionatingtower 1 The following conditions are illustrative of operation of thatpart of the illustrated apparatus so far described in detail: Raw gasoil is supplied to the mix-tank 14 through connection 13. Atemperatureof approximately 2230-290 F. and apressure` approximating -50 pounds persquare inch is maintained at the upper end of the fractionating tower 1.A furnace oil fraction is discharged through connection 37 in amountcorresponding` approximately to 20-22% of the raw gas oil suppliedthrough connection 13. A part of the condensed fraction separated in thefractionating tower 1 is pumped into the itransfer' connection 21through connection 20 at a rate suicient to maintain the temperature ofthe mixture entering the evaporator 12 through connecl tion 21 in theneighborhood of G50-680 F., and the balance of this fraction is suppliedto the mixtank 14 through connections 16 and 17. The stock mixture vfromthe mix-tank 14 is forced through the cracking heater 11 under pressuresuiiici'ent to maintain a pressure in the cracking heater discharge, inadvance of the valve 26, ap*- proximating 40o-600 pounds per squareinch, and in the cracking heater 11 this stock mixture is heated toamaximum temperature Aapproximating, for example, 925 F. The pressure onthe hot oil products discharged from the cracking heater l1 is reducedas these'hot oil products pass through the reducing valve 26, a pressurein the neighborhood of y-60 pounds per square inch being maintained inthe evaporator 12. The temperature in the upper end of the evaporator 12is regulated to separate, in evaporator 12, a tar of chosen gravity, 5A. P. I. for example. This temperature may approximate, for example;600- 625 F.

" Constituents higher boiling than suitable as components of thegasoline product are separated in the fractionating tower 1.Constituents of the uncondensed vapors and gases separated in thereceiver 3 suitable as components lof the gasoline product are recoveredas a condensate in the separator 6 and this condensate is combined withthe condensate separated in the receiver 3. Constituents of thiscondensate mixture lower boiling than 'suitable as components of thegasoline product'are separated in the fractionating tower 8. Thefraction remaining, of controlled boiling range, is then subjected todigestionI with an adlsorptive catalyst under maintained pressure and at'elevated temperature in the digester 10.

vThe uncondensed vapors and gases separated in the receiver-Spass, bymeans of connections 39, 40 and 41, through the compressor 4 and thecondenser 5`intothe separator 6. 'Higher boiling constituents of thismixture of vapors and gases arethus condensed and the condensatey isseparated in the separator 6. The remaining gas mixture is dischargedthrough connection 42. The condensate separated in the receiver 3 isforced, by VmeansY of pump 43, through the heat exj changer 7 andconnection 44 into the fractionating tower 8. Condensate separated inthe yseparator 6, discharged therefrom .through connection 475 iscombined with the condensate separated in the receiver 3 before thelatter enters the heat exchanger 7. The condensate mixture introducedinto the fractionating tower 8 through connection 44 is fractionatedtherein under a pressure subfstantially higher'than thatprevailing inthe receiver 3, the heat required to eiect thefractionationbeing'supplied by means of the heat exchanger 7 and there-boiler 9. A reux condenser 46 is provided for controlling theoperation of the fractionating tower 8, control being afforded byregulation of the rate at which an appropriate cooling medium iscirculated therethrough, by means of connections 47 and 48. Condensateformed in the reflux condenser 46 is returned, or refiuxed, to the upperpart of the fractionating tower 8 through connection 49, uncondensedvapors and gases being discharged through connection 42. The condensatemixture separated inthe lower part of the fractionating tower 8 passes,by means of connections 50 and 51, through the re-boiler 9 in which itis reheated, lower boiling constituents separated in the reboilerbeingreturned to the fractionating tower 8 through connection 52.V Thisreheating is accomplished by circulating steam, or other appropriateheating medium, through the coil 53. From the re-boiler 9, the remainingcondensate mixture is discharged to the digester 10, either throughheater 54 and connection 51 or directly through connections 55 and 51.Pressure is maintained throughthe fractionating tower 8 and the digester10 by means of valve 56 or valve 57 in the discharge connections fromthe digester 10. After passing through these valves or either of themthe pressure on the condensate mixture may be reduced, for example, to apressure approximating atmospheric pressure.

The following conditions are illustrative of operation of that part ofthe illustrated apparatus comprising the receiver 3, the separator 6,the fractionating tower 8 and the digester 10: Condensate is separatedfrom the uncondensed vapors and gases in the receiver 3 under a pressureapproximating 30-50 pounds per square inch, the temperatureapproximating 80 F. for example. A pressure approximating 250 pounds persquare inch and a temperature approximating 80 F. are maintained ink theseparator 6 by means of the compressor 4 and the condenser 5. Atemperatureof approximately 1 10-120" F. and a pressure approximating21o-220 pounds per square inch are maintainedat the upper end of thefractionating tower 8. The condensate mixture introduced throughconnection 44 is heated, by means 'ofthe heat exchanger 7, to atemperature approximating 270-280 F. as introduced. In the reboiler 9the condensate mixture is reheated to a temperature approximatingB20-350 F. A temperature of approximately 400 F. and a pressure'approximating 200-210 pounds per square inch are maintained in thedigester 10.

Pressures upwards of about 200 pounds per square inch are with advantagemaintained in the fractionating tower 8 and the digester 10. Atemperature in the neighborhood of 400 F. is with-advantage maintainedin the digester 10 when using fullers earth or similar clays as theadsorptive catalyst. f After passage through the digester 10, thegasoline product may be discharged directly through valve 56, connection53 and cooler or condenser 59, or it may be given a supplementarytreatment with anadsorptive catalyst at lower pressure in the, treatingtower 60.V This supplementary treatrnent may be carried out with theheat available in the product discharged from the digester 10, or thisproduct may be reheated in the heater 61 before entering the treatingtower 60.

It will be understood that two or more digesters corresponding todigester 10 may be provided, with appropriate connections, to permit theuse of one `digester as an alternate for the other as ius that other isbeing cleaned and recharged with fresh adsorptive catalyst. Similarly,two or more treating towers corresponding to tower 60 may be provided,with appropriate connections, to per mit the use of one as an alternatefor the other.

I claim:

1. In the manufacture of gasoline by cracking higher boiling hydrocarbonoils at temperatures exceeding 900 F. to produce cracked gasoline ofhigh anti-knock value, the improvement which comprises fractionating amixture of vapors and gases from the cracking operation proper toseparate therefrom constituents higher boiling than suitable ascomponents of the gasoline product, subjecting the remaining mixture ofvapors and gases to condensation and separating a condensate includingthe gasoline product from uncon-r densed vapors and gases, increasingthe pressure on this separated condensate and fractionating thecondensate under the increased pressure to separate therefromconstituents lower boiling than suitable as components of the gasolineproduct, digesting the remaining condensate with an adsorptive catalystunder maintainedV pressure and at a temperature not substantially lowerthan that at which it is discharged from the secondmentionedfractionating operation, and thereafter reducing the pressure on thedigested con` densate constitutingV the gasoline product..

2. In the manufacture of gasoline by cracking higher boiling hydrocarbonoils attemperatures exceeding 900 F. to produce cracked gasoline of highanti-knock value, the improvement which comprises fractionating amixture of vapors and gases from the cracking operation proper toseparate therefrom constituents higher boiling than suitable ascomponents of the gasoline product, subjecting the remaining mixture ofvapors and gases to condensation and separating a condensate includingthe gasoline product from uncondensed vapors and gases, increasing thepressure on the uncondensed vapors and gases and on this separatedcondensate, cooling the uncondensed vapors and gases and separating theresulting condensate, combining the two condensates and fractionatingthe condensate mixture under the increased pressure to separatetherefrom constituents lower boiling than suitable as components of thegasoline product, digesting the remaining condensate mixture with anadsorptive catalyst under maintained pressure and `at a temperature notsubstantially lower than that at f EUGENE C. HERTHEL.

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